(4.35E-2 - x)(7.56E-2 -x )

Question

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(0.324 + 2x)2

Rearrange to get an expression of the form ax2 + bx + c = 0 and use the quadratic formula (solve for x. This gives:
x = 1.05E-2, 0.143

basically i understand they use the quadratic equation but how did they change that crazy fraction into the quadratic formula?

Answer 1

If that fraction = 0 (you left that out) then the denominator is not part of the problem unless it is zero.

32.88 E-4 - 11.91 E-2 x + x^2 = 0

x = [ 11.91E-2 +/- sqrt(142 E-4 - 132 E-4) ] / 2

= [ .119 +/- E-2 sqrt(10) ]/2

= [.119 +/- .031 ]/2

= .075 or -.044

Answer 2

for the following population of n=9 scores below.
11 12 16 15 19 16 13 17 11
range........
variance standard deviation s: